Pulse signaling means



Jan. 1, 1952 R. SUEUR 2,580,973

PULSE SIGNALING MEANS Filed Aug. 7, 1947 M" Rene: SLLew" Ric L M,

Patented Jan. 1, I952 UNITED STAT s PATENT PULSE SIGNALING R-en Sneur, Paris-, France Application August 7 In France 1947,,SerialNo. 767,185 April'14, 1945 Sectionl, Public Law 690, August"8,,1946. Patent expires Apr-i114, 1965 Claims.

The present invention relates to signal transmitting systems, and more particularly to systems in which signals of a definite frequency to be retransmitted are likely to be superimposed by frequencies, particuiarly voice frequencies, which are not to be retransmitted.

Itis an object of the present invention to provide-a. simple circuit for blocking the frequene cies, particularly voice frequencies, which are not a to be retransmitted.

It is another object of the present inventionto provide a circuit of the kind described in which a device is connected inthe circuit for the frequencies to be blocked which has different time constants for charging and discharging. In. this Way'th'e signal transmitter is protected against operation caused by voice frequencies.

According to a preferred embodimentof the present: invention the time constant device. has amuch smaller time-constant for. charging than for discharging. Therefore it blocks the disturbing frequencies practically immediately.

Other objects of the present invention will become apparent from the following detailed (18'.- scription: thereof in connection with the accompanying drawings, in which.

Fig. 1 is a circuit diagram showing theprinciple of the present invention;

Fig. 2 is adiagram showing by way of example an embodiment of the present'invention; and

Fig. 3 is the current-voltage characteristic of the circuit shown in Fig. 2.

Referring now to the drawings and first to Fig. 1, it is seen that the circuit includes two branch circuits connected in parallel and presently to be described more in detail. The signals arrive at point a and are supplied to an amplifier .A. The output of amplifier A branches at b in .two branch circuits l and 2. includes a first detector D1 andleads at cv to the Branch circuit l output device including a vacuum tube system L and a relay 1- connected in series.

Branch circuit 2 includes a filter F, a second detector D2, and a device CR charged. by the detector D2 in series and leads at d to the output device to which the first branch circuit is connected. The filter F is tuned to pass all frequencies which are different from a predetermined frequency, say 2,000 cycles per sec., particularly voice frequencies. The device CR has different time constants for charging and discharging, preferably a relatively small time constant for charging and a relatively large time constant for discharging.

. The operation of this device is as follows:

Signals arrive at a and are amplified by the amplifier A. If the signals contain only the predetermined frequency which is not passed by the filter 'F, the signals proceed only along branch circuit I where they are rectified by detector D1. The rectified signals are supplied to 1y. Circuit l leads to the vacuum tube. system I which. energizes the relay r the armature of which moves in the rhythm of the signals and retransmits them.

If signals of any other frequency than the predetermined one, particularly of. voice frequency,

arrive at a, they are amplified by amplifier A and proceed partly along branch circuit I and partly along. branch circuit 2, since the filter F allows such frequencies to pass. The part of the signals. proceeding through branch circuit I tends to act on the vacuum tube system L in thesame way as if a signal of the predetermined frequency had arrived, but it is prevented from acting on system L by the part of the signals proceeding through branch circuit 2 which after passing, the filter F is rectified by detector D2 and supplied to the device CR. This device, owing to it's different time constants for charging and discharging, immediately blocks the system L against operation so that these signals are" not retransmitted. 1

Referring now to Fig. 2 showing a diagram of an embodiment. of r the present invention, the point a. of Fig. I is formed by the output of a transformer T0 to the primary of which are applied the arriving signals. The amplifier A of Fig; I is designed in Fig; 2'as a. vacuum tube 11 the controlgridof which is connected to the output" of transformer To. In the anodecircuit of tube ii the primaries of two transformers T1 and T2 are connected in series the secondaries of which feed the circuits 5 and 2., respectivethe detector D1 shown as a, two-wayrectifier-shunted by a resistance R1 the positive terminal of which is connected to the control grid of a vacuum tube is which corresponds to the tube system L of Fig. 1.

Branch circuit 2- leads first to a filter F consisting of a suitable combination ofinductances and condensers, and then to a detector Dz shown as a-twd-way rectifier. The filter'F allows any frequencydifferent from the predetermined frequency of, say, 2000cycles per second to pass. The rectifier Dz' feeds the rectified signals to a resistance R: the negative terminal of which is connectedtdacathode of a diode is the anode of which is connected over a condenser Ca. tc a resistance R2; A relatively large resistance R3 is connected in parallel to condenser C3. The junction of the anode of diode f2, condenser 63 and resistance R3 is connected to the control grid of 'tube- I3 to which the positive. terminal of resist- 'an'ce R1 is also connected. In the anode circuit 'of' tube Is the relay 1" of Fig. 1 is connected.

Preferably the'following numerical values are chosen for the resistances'and the condenser:

Rx. 500,000 ohms. C3,..3OX'10? farads R1, 2,500 ohms vR2, 5,000 ohms It will be readily understood that resistance R2, the diode is, condenser C3, and resistance R3 form together the device CR. of Fig. l. charging of the condenser is effected in a very short time dependent only on sistance R2 and condenser C3. The discharging time constant of condenser C3 is relatively large owing to the large value of resistance R3. The control grid of tube is which receives a positive bias from resistance R1, is biased by resistance Ra in a negative sense overcoming the bias by resistance R1 whenever signals arrive which contain frequencies different from the predetermined frequency of, say, 2000 cycles per second. The negative biasing of the control grid of tube I, is effected almost instantaneously upon the arrival cf signals having frequencies different from the predetermined frequency and the negative bias is maintained for some time owing to the large discharging time constant of condenser C3.

With the numerical values given hereabove the tube [3 receives a negative grid bias except for frequencies between 1,950 and 2,050 cycles per second. 1

Referring now to Fig. 3 showing the current 2' in the relay r as a function of the voltage 1) of the wave trains at the input of the transmitting device, it will be seen that the maximum distor: tion of the signals amounts to An extensive testing of the circuit according to the invention has shown that voice frequencies, such as those of spoken words, do not cause an operation of the signalling system.

If desired, the filter F may be tuned to block any frequency differing from a plurality of predetermined frequencies.

What I, claim is:

1. In a system for transmitting a predetermined desired signal frequency substantially to the exclusion of disturbing frequencies, a common input channel, a transmission channel, means for coupling said transmission channel to said input channel for transmitting both said signal frequency and said disturbing frequencies, a blocking channel, means coupling said blocking channel to said input channel, a signal transfer device adapted to be controlled by a potential applied thereto, means coupling said transfer device to said transmission channel and to said blocking channel, filter means in said blocking channel for rejecting said desired signal frequency and for passing said disturbing frequencies. and means-including a time constant circuit in said blocking channel for producing a potential from said disturbing frequencies and for applying such potential to said transfer device to render it incapable of transferring said distributing frequencies from said .transmission channel.

2. In a system for transmitting a predetermined desired signal frequency substantially to the exclusion of disturbing frequencies, a common input channel, a transmission channel, means for coupling said transmission channel to said input channel for transmitting both said signal frequency and said disturbing frequencies, a blocking channel, means coupling said blocking channel to said input channel, a controllable electron tube, means connecting said tube to said transmission channel and to said blocking channel, filter means in said blocking channel. for rejecting said desired signal frequency and for passing said disturbing frequen- The p the values of recies, and means including a time constant circuit in said blocking channel for producing a potential from said disturbing frequencies and for apput circuit of said plying such potential to said tube to render said tube incapable of transferring such frequencies from said transmission channel, said time constant circuit having a relatively small time constant for charging and a relatively large time constant for discharging.

3. In a system for transmitting a predetermined desired signal frequency substantially to the exclusion of disturbing frequencies, a common input channel, a transmission channel, means for coupling said transmission channel to said input channel for transmitting both said signal frequency and said disturbing frequencies, a grid-controlled electron tube and means connecting its input circuit to the output of said transmission channel, a blocking channel, means coupling said blocking channel to said input channel, filter means in said blocking channel for rejecting said desired signal frequency and for passing said disturbing frequencies, and means in said blocking channel including a time constant circuit connected to the input circuit of said tube for producing from said disturbing frequencies a potential effective to render said tube incapable of transferring such frequencies from said trans mission channel, said time constant circuit having a relatively small time constant for charging and a relatively large time constant for discharging.

4. In a system for transmitting a predetermined desired signal frequency substantially to the exclusion of disturbing frequencies, acommon input channel, a transmission channel, means for coupling said transmission channel to said input channel for transmitting both said signal frequency, and said disturbing frequencies, rectifier means and an output impedance in said transmission channel, a grid-controlled electron tube and means connecting its input circuit to said output impedance, a blocking channel, means coupling said blocking channel to said input channel, filter means in said blocking channel for rejecting said desired signal frequency and for passing said disturbing frequencies, rectifier means in said blocking channel connected to said filter means, a time constant circuit in said blocking channel connected to said rectifier means and operative to produce from said disturbing frequencies a potential capable of stopping signal transfer my said tube, and means connecting said time constant circuit to the in- I tube so as to render the tube incapable of transferring disturbing frequencies from said transmission channel.

5. A system as defined in claim 4, wherein said time constant circuit includes a condenser and a large resistor in shunt therewith.

V RENE: SUEUR."

REFERENCES orrsn The following references are of record in the file of this patentt UNITED STATES PATENTS 2,282,131 Hadfield May 5, 1942 

